Clearwire and Sprint-Nextel announced Monday they have completed their joint-venture transaction and will offer mobile WiMax service under the "Clear" brand.

The transaction, announced in May, creates a new company valued at $14.5 billion, formed with the WiMax assets of both Sprint-Nextel and Clearwire. The new company aims to create a nationwide broadband wireless network to rival AT&T.

As part of that plan, the new company will retain the Clearwire name and offer mobile WiMax under the Clear brand. Over the coming months, Sprint Nextel's XOHM service will undergo a name change.

The newly company aims to offer an open all-IP network that features mobile WiMax technology with download speeds of 2 to 4 megabits per second. The open IP (Internet protocol) will be designed to allow any WiMax device to connect to the network, said Clearwire CEO Benjamin Wolff during a conference call to announce the closing of the transaction.

He added the new Clearwire also aims to offer greater spectrum and an all IP-network to bolster its network capacity and improve performance.

"We are the underdog," Wolff said, but noted the steps Clearwire is taking will prompt other companies to hold similar aspirations.

The new company is also working on launching a nationwide 4G wireless broadband network using WiMax, which aims to run five times faster than 3G technology. The combined spectrum holdings of the new company provide it with 100 MHz, or more of potential 4G spectrum in most U.S. markets.

Clearwire, as it has previously laid out, will receive a $3.2 billion investment from Comcast, Intel Capital, Time Warner Cable, Google, and Bright House Networks, as well as an additional investment from Trilogy Equity Partners in the coming months.

The newly formed company expects to begin making upgrades to its mobile WiMax network early next year.